Army ants, a study in social behavior.
Publication date 1968
Publisher Chicago : Encyclopaedia Britannica Educational Corporation
Digitizing sponsor Internet Archive
Contributor Internet Archive
Chief scientific adviser, Ralph Buchsbaum; collaborator, T. C. Schneirla
Documents the complex organization and social behavior of two species of army ants and shows how a naturalist works
Ocr This film is. About two species of tropical American hands was patterns of behaviour then evolving for more than fifteen million years. They represent a highly advanced form of social behavior. Knowledge of which contributes to our general theories of animal behavior. It's. So. How. Can we understand the organization of colony life in these ants. The scientist ways is to make observations in the natural environment. To repeat an observation many times and to conduct experimental tests in the field and in the laboratory under controlled conditions over a long period of time. Following an army and column in the dim light than tangled growth of the forest is not an easy course but it is the only way to find the home site or bivouac of the colony. Occur and they consist of a queen and many thousands of workers. This golden yellow and is the surface adapted species as a consummate them. By clustering together the workers form the walls and inner structure of the nest with their own bodies. No other materials are used. Except the natural supports to which they claim. Nearly all the ants hang head downward in the structure. Opposed double hooks at the end of each leg. Unable the ants to hold on to different services and to interlock their bodies. The big whack or temporary in this is the place where the study of these insect colonies begins. From each bed lacks the colony carries out its great rate of the day and emigrates at night. How connectivity is so complex Lee organized and highly adaptive as these be accomplished by creatures as simple as army ants are in their individual behavior. We will start our observations with the beginning of activities in early morning. When the first light reaches the bed lack wall it stimulates and excites the ants. Once aroused the workers begin to leave the cluster for the ground. This army and Colony is the species known as S. a time virtually It too is adapted to live above ground. This bubble act is about one meter in wits. In this observation. Bluing on the bivouac wall excites an agitated the ants wind or rain would have a similar effect causing the big black to shift a little. Each morning workers numbering some hundreds of thousands as in the species. Swarm from the battle axe to pillage for food on the forest floor. Says their numbers increase on the ground the answer pushed ahead by the pressure of those behind. The sounds you hear are those of emperors they eat insects. Stirred up by the foraging ants. Their calls are useful clue for locating an ant's warns. During the great exodus from the bed lack at the beginning of the raid the amps warm out in all directions from the nest. Gradually this movement turns toward the dominant sector. And coming in from other areas. Move in columns and connect with the developing a swarm or the devil asked see. As the ants move farther from the big whack the pattern of the raid takes a roughly triangular or fan like form with only a single broad column connecting to the big whack. It's at the height of the radius the answer this warm front may cover an area more than fifteen metres wide and one to two meters deep. They stream along the ground. Prepping under every leaf and in every crannies for practically any living creatures. Unless very agile. Few soft bodied insects escape the fast moving events. It's. Few obstacles in the terrain stand in the way of their attacks. They. Advance arrest tangle. Even climbing to the top most branches of trees. Capturing their prey. Whenever an insect such as this katydid is overrun it is torn to pieces so that it can be easily carried. By pulling together from all sides the ants dismember their booty they attack anything that moves under the weight of ants. Most efforts to escape are futile. This large and predatory pioneering ant will be fought strong men taken apart limb by limb. The buzzing of flies of various species is another characteristic sound accompanying us warm rain. By mid-morning the booty Laden ants crowd the principle trails as they move towards a bit of whack. Parts of insects and other arthropods such as eggs. Live others and to pose of wasps and aunts are holed a long in the procession. How do the ants find their way with all the confusion that seems to exist in these masses of scurrying body use see. There are no leaders yet at the height of the raid the ants may be out ninety meters or more from the bed lack. Here's a simple test that may give us a clue. It's. See. Why do the ant stop short when the leaf is removed. Why. Do they continue when it is returns doesn't the action indicate that perhaps this is an older trail and that chemical products on the ground. Mark the way. We will try a similar test with the other and species. Again behavior shows that a crucial stimulus has been removed. How can the train will be restored. From this and other experiments we find that the excited and leaves a chemical trail on the ground over which it moves. Once this basic sense as laid down by the first dance that move into new ground. Sensitivity to chemical stimulation permits others to follow. Seven difficult time returning. If the answer forced into moving on outlying trails they often deposit their loads in booty caches. These storage areas may contain as much as a gallon them slaughtered food. Clothes him toward the bevel X. branching trails have disappeared leaving only a principal trail. Over this now heavily traveled and chemically saturated bath Laden workers bring food to the brood Queen and other inhabitants of the colony. At times returning traffic may be dominated by unladen ants. They have simply been moving back and forth. Following the scent of others on the trail. This colony is in the state arrays or non migratory Ses of its nomadic existence. During this phase which lasts about three weeks. It remains clustered in the same sheltered site now maturing a pupil brood and undergoing early reproductive stages of a new bruises. What is the nature of the population living in this best way. To find out we will take a sample for later study in the laboratory. Swirling the bag rolled the ants into a ball which can be poured into an observational frame one important section of the population is the brood it is present in any functional colony here is a small part of the brute in the pupils stage attended by workers. In each colony there is one fertile queen who is the source of the immense brood depending on the species. She may lay is sixty thousand to two hundred thousand eggs in each reproductive period that. All workers are infertile females and all are polymer thick but is they differ in both size and form in the species they range from three millimeters to thirteen and a half millimeters in length. Major is are the largest workers. Intermediate workers are the most numerous. They do the largest part of the effective rating. Minimums the smallest workers spend most of their time tending the small brood within the big whack. Size appears to depend upon the order in which the eggs are hatched and the amount of food which larva has received the first live as to begin feeding receive the most food and grow to be majors. They are characterized by their enormous heads and large sickos sake man the bills these needle sharp jaws together with potent Sting are enough to keep most intruders away. Minimums the last to hatch are fed the least amount of food. The state or a phase of colony behavior NS When a brood of new young workers. Emerges from the cocoons. Knowledge the nomadic phase begins with daytime raids ending in nighttime emigration Zz two new nesting sites. But talk with a was possible only with battery powered lights. In late afternoon exodus from the bevel act again this. As the excitement mounts and soaked into the bed lack wallet are released by the departure of other ants. As the cluster gradually breaks down they pour from the nest and emigration begins overrating trail developed during the day. Late Rader is returning to the bed lack are forced to change direction by the outgoing rush of traffic. These anagrams are moving their own larva is together with booty. During most of the year. Successive broods contain only developing workers the ants carry the larva isn't booty in their jaws. Slung under their bodies. Size of the worker is roughly determines the size of the loads they carry. Except that Major is never seem to carry anything. They often appear to get in the way of others. At the beginning of the dry season a bisexual brute of a great many males and a few young Queens develops. Here the workers are carrying the very large male learners of the sexual brewed. In rough sections of the trail. McCullum crosses on bridges made up of the body is of clustered workers. The large answer running in the column are when get mails. Development of a sexual brood of new queens and wing of males leads to a splitting of the colony into two new ones and important part of population control in army ants. This emigration will be complete only when the entire colony is settled in a new place. These ants are entering and adding to the structure of the new better way. Nomadic that blacks are not sheltered but are usually out in the open. In the nomadic phase. Emigration such as this. Go on every night for more than two weeks. Usually before midnight a change in the character of the moving column indicates passage of the Queen and her party she moves slowly under her own power through the masses of workers that surge over and around her. But why do the workers respond so excited late to her presence. Is this a chemical effect also. Let's try another laboratory test. In this frame to circular areas have been marked. A queen has been resting on one of these areas for one or the other is our control. Now we remove the queen and her confining cover. Opening the closed to black tunnel. Permits the ants to enter. Within a short period of time it is clear that the workers are strongly attracted to their Queen's order. In this test. Note how the workers follow the queen in a circular come another queen responds to the chemical trail much as does a worker. Now it will return a queen to the natural environment by releasing her close to a rating column of her calmness. Slowly a few workers are attracted to her order. The many that follow and cluster over indicate that the Queen's odor is a central factor in column the unity. If the queen had not been returned. Brew developments and consequently the nomadic function of the colonies would end. Without a queen. The colony can survive only by a fusion with another colony of the same species. These scenes of army ants in action. Illustrate how methods of field and laboratory research has been used to study problems of insect social behavior. Research on the swarm raids for example reveals how complex mass actions are organized through group interactions of relatively simple individuals. Perhaps the most remarkable finding about tropical army ants. Concerns the nomadic stater recycles shown by species adapted to service life. A company is no magic when it is stimulated to a high pitched by its active brood in the level condition. It is stated arrayed in the intervening time when the brood is and its people stayed. As Brood follows brewed through the year. Each colony passes through these successive cycles. There are other kinds of army ants whose patterns of life are not as well known as those you have seen many species which nest underground as does Labor has printed but in the behavioral problems for future investigation.
Run time 18:56
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Worldcat (source edition) 3880019